Evaluation of Lightning Backflashover Rate of a Fully Composite Pylon using Monte Carlo Method on Environmental Factors

Design of a 400 kV fully composite pylon with external down-leads to bring grounding potential to earth wires has been proposed to meet the requirements of saving lines corridors and reducing visual impact. The backflashover performance of the pylon is investigated by EMT and the Monte Carlo method is employed on lightning current waveform parameters and soil resistivity. The backflashover rates of the pylon are estimated for different soil conditions and ground flash density in a broad variation. A case study in Denmark is exampled and compared with the backflashover rate of a conventional transmission tower. Because of the non-linearity of the relationship between backflashover probability and the value of soil resistivity, selecting constant soil resistivity for transmission tower footing model in high-resistivity region may overestimate the BFR.